oa USING BACTERIAL HOPANOIDS TO FINGERPRINT PEAT-DERIVED ORGANIC MATTER ALONG THE TERRESTRIAL-AQUATIC CONTINUUM

Peat is a heterogeneous mixture of (partly) decomposed plant material that forms large carbon stores. However, if peat-derived organic carbon (OCpeat) is eroded and transported along the terrestrial-aquatic continuum, it may act as a source of carbon to the atmosphere. Modern observational evidence suggests that carbon losses from peatlands are significant and an increasing component of the global carbon cycle ( Moore et al., 2013 ). Although relatively well-constrained at present, the transfer of OCpeat along the terrestrial-aquatic continuum remains poorly constrained in ancient settings. Radiocarbon measurements can be used to distinguish between fresh OC and older peat-derived OC ( Moore et al. 2013 ). However, because the half-life of 14C is relatively short, this approach cannot be used beyond ∼50,000 years and alternative techniques are needed to probe this during different climate states, e.g. greenhouse climates of the Eocene. Here we explore whether the stereochemical properties of bacterial hopanoids can be used to fingerprint peat-derived OM along the terrestrial-aquatic continuum.